Copper toxicity is most likely to occur when which process is impaired?

• A. Increased intestinal absorption
• B. Impaired biliary excretion
• C. Increased urinary excretion
• D. Enhanced hepatic copper storage

Answer: (B)

Copper toxicity occurs when the body’s primary elimination route—biliary excretion—is impaired. Most copper that enters the body is taken up by the liver and then excreted into bile for elimination in the feces. If this biliary pathway is defective, copper cannot be effectively dumped into the bile, so it accumulates in hepatocytes and eventually can spill into the bloodstream, causing cellular injury and systemic toxicity. This is seen in conditions like Wilson disease, where a defect in the transporter that moves copper into bile disrupts excretion and ceruloplasmin incorporation, leading to copper buildup in the liver and beyond.

Increasing intestinal absorption would raise load but is usually countered by biliary excretion; increasing urinary excretion is not the primary route of copper elimination, so it would not be the main driver of toxicity; and simply enhanced hepatic storage reflects a consequence of impaired excretion rather than the initiating process.